1. Field of the Invention
The present invention relates, in general, to electric power service to homes and buildings and, more specifically, to watthour meters and meter socket adapters mountable in watthour meter sockets at homes and buildings.
2. Description of the Art
Electrical power is supplied to an individual site or service by external electrical power line conductors located above or below ground. In a conventional arrangement, electrical power line conductors are connected to contacts in a watthour meter socket mounted on a building wall. Electrical load conductors are connected to another set of contacts in the meter socket and extend to the electrical distribution network in the building. A watthour meter is connected into the contacts in the meter socket to measure the electric power drawn through the load conductors.
Due to the current trend toward the use of plug-in watthour meters, extender type socket adapters have been devised which allow the addition of equipment and features not originally intended for the electrical service. Such watthour meter socket adapters have been constructed as service limiting adapters and provided with power disconnect devices, such as circuit breakers or ground fault circuit interrupters, both for protecting the electrical service as well as, in certain applications, to limit the amount of power supplied to the use site.
It is common in the electrical utility industry to frequently disconnect electrical service to a particularly user site. Such service disconnection can be for non-payment, seasonal usage, or rental units in high turnaround areas, such as college campuses, mobile home parks and apartments, etc. Typically, when it is desired to disconnect electrical service to a particular user site, a utility meter person goes out to the particular user site and removes the watthour meter. Another meter person must be sent out to re-install a meter to reconnect service to the user site. This sequence is labor intensive and, therefore, expensive.
The remote watthour meter reading controllers now being installed in electrical distribution networks have the capability of remote disconnect and reconnect. It is also known to provide such meter reading controllers and service limiting adapters with external signals to enable the electrical power utility to selectively activate a relay in the adapter to disconnect power to a specific use site. Such externally controlled relays have typically used low level DC voltage signals which switch the relay in the socket adapter to an "off" position opening the current path through the line and load circuits.
Many electric utilities have rules that will not allow a reconnection of a meter if the electric customer is not at home or if the main power disconnect is not turned off. This is for safety reasons since a box or other combustible material could be left on a stove that may be switched on and could start a fire when the meter is reconnected. Combustible material may be left near a turned on electric heating source or a water pump which is turned on, but not primed, both creating potential fire hazards when the watthour meter is reconnected.
Even when electric power is allowed to be turned back on when the electric customer is not home, a standard test out procedure is commonly employed to make sure there is no hazards or faults, such as miswired service or a back feed condition, such as occurs when power is borrowed from a neighbor for temporary use. The test out procedure is also performed since the electric service is typically only protected for faults or overcurrents at the primary, such as the primary of a transformer servicing many customers. This can allow many times the available power if the meter is reconnected into a fault condition.
The new switch adapters used to disconnect and reconnect electric power service do not have overcurrent protection. Such switch adapters can be wired to allow the switch to be reset at the adapter with an add-on electrical pushbutton or plunger. This would place the electric customer in the position of reconnecting electric power at the socket without testing for a fault. This is a situation which many utility companies would not presently allow thereby requiring the meter service person to preform tests because of the potential fire and safety hazards.
Such power disconnects or circuit breakers have been mounted in a watthour meter socket adapter housing by means of fasteners, such as nuts and bolts. As circuit breakers are sized to protect the service entrance conductors, circuit breakers have been previously available in a number of current trip capacities, such as 60, 100, or 150 amp service. Any upgrade in the service current carrying capability would require a different circuit breaker. This necessarily would then require a new socket adapter with the new circuit breaker or the removal of the circuit breaker from the existing socket adapter at a service site and the mounting of a new circuit breaker with a higher current rating in the socket adapter housing.
Present technology is now able to make power disconnect switches or circuit breakers operable up to 160 amps continuous service. It would be desirable to provide a circuit breaker or power disconnect switch for a watthour meter socket adapter which can carry the highest possible continuous current and still be mountable within an existing socket adapter housing without significant modification to the housing.
Separate from the electrical utility industry, shunt type circuit breakers are used as electrical control devices. Such shunt type circuit breakers have input terminals to which 120/240 VAC may be applied to trigger the circuit breaker coil and switch the circuit breaker contacts from closed to open positions. When power is applied to the trigger terminals of shunt type circuit breakers, the shunt type circuit breaker goes into a stand-by condition which prevents the manual actuator on the circuit breaker from being pushed to a reset position to close the internal circuit breaker contacts which would allow the reapplication of power to the use site. However, once power is removed from the trigger circuit, the circuit breaker can be manually reset to the power "on" or contacts closed position.
As such, it would be desirable to provide a circuit breaker switch apparatus which includes means for mounting a circuit breaker in a watthour meter socket adapter which is capable of operating with 120/240 VAC input trigger signals. It would also be desirable to provide a means for mounting a shunt type circuit breaker in a watthour meter socket adapter without extensive modification to the existing socket adapter housing. It would be desirable to provide a limiting electrical service adapter which includes means for safely remotely disconnecting and reconnecting electrical power to a use site. It would also be desirable to provide a circuit breaker switch apparatus which can be removably mounted in a watthour meter socket adapter housing, through a snap in connection. It would also be desirable to provide a circuit breaker for mounting in a watthour meter socket adapter which enables higher current rated bus bar type electrical conductors to be easily and quickly attached to the circuit breaker terminals.